Very long‐term follow‐up results of imatinib mesylate therapy in chronic phase chronic myeloid leukemia after failure of interferon alpha therapy

BACKGROUND: The long‐term outcome of patients with chronic phase chronic myeloid leukemia treated with imatinib after failure of interferon alpha therapy has not been detailed. METHODS: In total, 368 patients were analyzed. Univariate and multivariate survival analyses were conducted using standard statistical methods. RESULTS: Overall, 247 patients (67%) achieved a complete cytogenetic response (CCyR). Of the 327 patients who were studied, 207 patients (63%) achieved a major molecular response (MMR), and 99 patients (30%) had undetectable breakpoint cluster region/c‐abl oncogene (BCR‐ABL) levels at some time during therapy. The estimated 10‐year survival rate was 68%, the progression‐free survival rate was 67%, and the event‐free survival rate was 51%. In multivariate analysis, age ≥60 years, hemoglobin <10 g/dL, bone marrow basophils ≥5%, any peripheral blasts, and clonal evolution were independent adverse factors for survival. The estimated 7‐year survival rate according to the presence of no factors (n = 154), 1 or 2 factors (n = 190), or ≥3 factors (n = 24) were 93%, 70%, and 25%, respectively ( P < .01). Achieving an MMR, a CCyR, or a partial cytogenetic response at 12 months was associated with significantly better 10‐year survival rate in a landmark analysis (10‐year survival rate, 80%‐90%) compared with achieving a minor cytogenetic response or a complete hematologic response (10‐year survival rate, 55%‐65%) or another response (10‐year survival rate, 10%). In a landmark analysis that included imatinib response at 12 months, achieving a major cytogenetic response or better (hazard ratio, 0.12; P < .001) and achieving a complete hematologic response or a minor cytogenetic response (hazard ratio, 0.36; P = .003) were significant favorable prognostic factors. CONCLUSIONS: The current results indicated that the estimated 10‐year survival rate of 68% for patients with chronic myeloid leukemia who receive imatinib after failure on interferon has improved. Cancer 2012;118: 3116–22. © 2011 American Cancer Society.